Maximizing syngas carbon utilization and conversion to biofuels

Abstract

A method is provided for optimizing syngas carbon utilization and syngas purity from various scrubbed syngas sources prior to supply to a syngas conversion unit, the method comprising: supplying the scrubbed syngas to a purification unit comprising at least one absorption unit to remove CO2 from the scrubbed syngas to produce a clean CO+H2+CO2 syngas stream and a CO2-rich stream; and mixing the clean CO+H2+CO2 syngas stream with hydrogen to produce a balanced syngas stream, where the balanced syngas stream meets the stoichiometric ratio and purity requirements of the syngas conversion unit.

Description

[Technical field]

[0001] Methods are provided for optimizing syngas carbon utilization, syngas purity, and syngas conversion to subsequent downstream syngas conversion units. [Background technology]

[0002] Methanol production from synthesis gas is a well-known technique. Traditionally, such synthesis gas has been produced from coal gasification, natural gas reforming, or other fossil fuel gasification, or catalytic and / or thermal reforming.

[0003] Syngas has also been demonstrated to be produced from similar gasification and / or reforming techniques using bio-carbonaceous feedstocks such as biomass (e.g., wood, agricultural residues, or fast-growing crops), plastics, biomass-rich residues, and / or wastes. Syngas production has been used to produce alcohols (such as methanol, ethanol, and propanol), drop-in fuels (e.g., hydrocarbons), and / or other chemicals (e.g., acetic acid, acrylic acid, or methyl acetate).

[0004] Some carbonaceous solid or liquid feedstock gasification and / or reforming technologies ultimately generate a crude synthesis gas stream with a H2 / CO ratio of less than 2.0, which is required according to stoichiometry for the production of methanol, alcohols, and Fischer-Tropsch. The H2 / CO ratios produced from these processes are often less than 1.5, and even as low as 0.7 or less.

[0005] In coal or liquid fossil fuel gasification and / or reforming plants that produce a raw syngas with lower H2 / CO than required according to the ratio resulting from the stoichiometric reaction of the desired end product, a water gas shift reactor is typically included in the plant design to shift some of the excess CO to additional H2 to re-equilibrate the overall plant H2 / CO ratio (according to reaction 1 below). This water gas shift reactor also produces CO2 as a by-product. Since the overall plant has excess CO2, a process unit is required for CO2 removal. The feedstock also typically contains sulfur, which is converted to reduced sulfur species (H2S, COS, etc.) in the gasification and / or reforming unit, and such typical plants also include an acid gas removal (AGR) unit that removes both CO2 and sulfur species. Sulfur species are a pollutant or poison for some syngas conversion catalysts and are also undesired in most final chemical and / or fuel products. CO+H2O⇔CO2+H2(1)

[0006] Depending on the particular catalyst and / or the desired end product, nitrogen contaminants such as HCN, NH3, and / or amines must also be removed from the syngas. Such nitrogen contaminants can also be removed in an acid gas removal unit, either in combination with or without other techniques. Commercially available cobalt-based Fischer-Tropsch catalysts are an example of a catalyst that can only tolerate ultra-low levels of such nitrogen contaminants, while also needing to achieve ultra-low levels of sulfur contaminants. Removal of nitrogen contaminants from the syngas can also benefit other syngas conversion technologies, such as methanol or ethanol, and can prevent trimethylamine (TMA) formation from the reaction of methanol with NH3, and subsequent additional purification efforts to remove TMA from the final desired product.

[0007] In biomass, biomass-rich or waste gasification and / or reforming valorization plants, such an approach has the adverse effect of losing valuable biogenic carbon via the carbon monoxide shift (Equation 1), which results not in a final biogenic product, but rather in excess CO2 (which the plant must valorize as very low value commercial CO2 and / or safely release to the atmosphere after processing), increasing the greenhouse impact of the plant. This also applies to the gasification of plastic-rich waste, waste (containing significant non-bio fractions), or non-bio fossil-derived waste.

[0008] Thus, there remains a need to provide methods to improve yields by minimizing carbon loss (mostly as CO) and maximizing overall carbon syngas conversion, as well as improve the conversion of carbon feedstocks to final desired products. Summary of the Invention

[0009] A method is provided for optimizing syngas carbon utilization, syngas purity, and syngas conversion from a scrubbed syngas source to a subsequent downstream syngas conversion unit, the method comprising: supplying the scrubbed syngas to a purification unit comprising at least one absorption unit to partially remove CO2 from the scrubbed syngas to produce a clean syngas stream and a CO2-rich stream; mixing the clean syngas stream with hydrogen to produce a balanced syngas stream, where the balanced syngas stream meets the stoichiometric ratio requirements of a syngas conversion unit; and supplying the balanced syngas stream to the syngas conversion unit.

[0010] In one embodiment, at least one absorption unit further removes sulfur species and produces an additional sulfur species-rich stream.

[0011] In further embodiments, the sulfur species is H2S, COS, CS2, or a combination thereof.

[0012] In another embodiment, the at least one absorption unit further removes nitrogen contaminant species that are combined with the sulfur species-rich stream or produces an additional nitrogen contaminant-rich stream.

[0013] In one embodiment, the various scrubbed syngas sources include 25-45 mol % H2, 30-65 mol % CO, and 6-40 mol % CO2.

[0014] In a further embodiment, the clean syngas stream composition comprises 30%-50 mol% H2, 40-68 mol% CO, and 0-25 mol% CO2.

[0015] In a further embodiment, the optimized carbon content (CO+CO) in the carbon recovery equilibrium syngas allows for an increase in the conversion of scrubbed syngas carbon to final desired products of more than 65%.

[0016] In one embodiment, the method described herein further comprises recycling the CO2-rich stream upstream of the purification unit, preferably to a gasification unit, for use as an inert gas, exporting the CO2-rich stream for Carbon Capture and Storage (CCS), and / or producing saleable commercial CO2 from the CO2-rich stream.

[0017] In a particular embodiment, the purification unit is an acid gas removal unit (AGR) comprising a selective solvent for absorbing CO and sulfur species from a scrubbed syngas in an absorption unit using the selective solvent to produce a loaded solvent and a clean syngas stream, removing the loaded solvent through at least one recycle loop, pre-flashing the loaded solvent at an intermediate pressure to recover absorbed H and CO, producing a H and CO rich CO stream and a flashed solvent vapor, flashing the flashed solvent at a lower pressure to recover CO, generating a non-combustible CO rich stream and a second flashed solvent, stripping the second flashed solvent in a first stripping unit to remove sulfur species, and producing a rich sulfur species stream and a clean solvent that is recycled to the absorption unit.

[0018] In a further embodiment, a first portion of the loaded solvent is removed through a first recirculation loop, a second portion of the loaded solvent is removed through a second recirculation loop, the first portion of the loaded solvent is pre-flashed at an intermediate pressure to recover H and CO contained in the loaded solvent and produce a first CO stream rich in H and CO and a first flashed solvent, and a second portion of the loaded solvent is pre-flashed at an intermediate pressure to recover H and CO contained in the loaded solvent and produce a second CO stream rich in H and CO and a second flashed solvent. a first flashed solvent, flashing the first flashed solvent at a lower pressure to generate a non-flammable CO2-rich stream and a clean solvent which is recycled to the absorption unit; recycling the H2- and CO-rich first CO2 stream and the second CO2 stream into the scrubbed syngas stream upstream of the absorption unit; and stripping the second flashed solvent in a stripping unit to remove sulfur contaminants (e.g., H2S, COS, etc.) to generate an H2S-rich stream and a clean solvent which is recycled to the absorption unit.

[0019] In another embodiment, the purification unit is an acid gas removal unit (AGR) comprising a selective solvent for absorbing CO, sulfur and nitrogen species from a scrubbed syngas in an absorption unit to produce a loaded solvent and a clean syngas stream, removing the loaded solvent through at least one recycle loop, pre-flashing the loaded solvent at an intermediate pressure to recover absorbed H and CO, producing a H and CO rich CO stream and a flashed solvent vapor, flashing the flashed solvent at a lower pressure to recover CO, generating a non-combustible CO rich stream and a second flash solvent, stripping the second flash solvent in a stripping unit to remove sulfur and nitrogen species, and producing a rich sulfur and nitrogen species stream and a clean solvent that is recycled to the absorption unit.

[0020] In another embodiment, a first portion of the loading solvent is removed through a first recirculation loop, a second portion of the loading solvent is removed through a second recirculation loop, a third portion of the loading solvent is removed through a third recirculation loop, the first portion of the loading solvent is pre-flashed at an intermediate pressure to recover H and CO contained in the loading solvent and generate a first CO stream rich in H and CO and a first flashed solvent, the second portion of the loading solvent is pre-flashed at an intermediate pressure to recover H and CO contained in the loading solvent and generate a second CO stream rich in H and CO and a second flashed solvent, and optionally the third portion of the loading solvent is pre-flashed at an intermediate pressure to recover H and CO contained in the loading solvent and generate a second CO stream rich in H and CO and a second flashed solvent. to recover H2 and CO contained in the loaded solvent to produce a third CO2 stream rich in H2 and CO and a third flashed solvent; flashing the first flashed solvent at a lower pressure to generate a non-flammable CO2-rich stream and a clean solvent which is recycled to the absorption unit; recycling the first CO2 stream rich in H2 and CO, the second CO2 stream, and the optional third CO2 stream into the scrubbed synthesis gas stream upstream of the absorption unit; stripping the second flashed solvent and the third flashed solvent in a stripping unit to remove sulfur and nitrogen species to produce a rich sulfur and nitrogen species stream and a clean solvent which is recycled to the absorption unit.

[0021] In a further embodiment, a third portion of the loaded solvent is removed through a third recycle loop. The third portion of the loaded solvent is pre-flashed at an intermediate pressure to recover H2 and CO contained in the third loaded solvent, producing a third CO2 stream rich in H2 and CO, and a third flashed solvent. The third CO2 stream rich in H2 and CO is recycled into the scrubbed syngas stream upstream of the absorption unit. The third flashed solvent is stripped to remove NH3 and HCN in the same stripping unit as the second flashed solvent, producing a stream rich in H2S, COS, NH3, and / or HCN (i.e., syngas pollutants) and a combined clean solvent that is recycled to the absorption unit.

[0022] In a further embodiment, the third flashed solvent is stripped in a second separate stripping unit to remove NH3 and / or HCN to produce an NH3 and / or HCN rich stream.

[0023] In one embodiment, the first stripping unit and / or the second stripping unit are thermal strippers that remove sulfur and / or nitrogen species to produce a sulfur-rich and / or nitrogen-rich gas stream and a clean solvent, which is recycled to at least one absorption unit.

[0024] In one embodiment, the stripping unit is a thermal stripper that removes sulfur contaminants to produce a rich H2S and / or sulfur contaminant gas stream and clean solvent, which is recycled to at least one absorption unit.

[0025] In one embodiment, the second stripping unit is a thermal stripper that removes nitrogen contaminants to produce a rich NH3 and / or HCN gas stream and clean solvent, which is recycled to at least one absorption unit.

[0026] In another embodiment, the solvent loop flow rate and temperature, as well as the pressure of the pre-flashing step, are adjusted to achieve a target CO2 content in the final clean syngas stream.

[0027] In further embodiments, the sulfur species is H2S, COS, CS2, or a combination thereof.

[0028] In additional embodiments, the nitrogen contaminant species is HCN, NH3, an amine, or a combination thereof.

[0029] In one embodiment, the scrubbed syngas source has a yield, flow rate, and / or composition that varies over time.

[0030] In further embodiments, the variability in the scrubbed syngas source is due to the variable nature of the heterogeneous waste biomass, waste, and / or plastic waste feedstocks.

[0031] In one embodiment, the clean solvent is cooled before being recycled to the at least one absorption unit.

[0032] In another embodiment, the thermal stripper comprises a column including a reboiler and a condenser.

[0033] In one embodiment, the non-combustible CO2 rich stream is further used as an inert gas, captured for carbon capture and storage (CCS), and / or produces commercial CO2 that can be sold.

[0034] In a complementary embodiment, the method further comprises treating the clean syngas stream with at least one solid adsorbent bed before or after mixing the clean syngas stream with hydrogen.

[0035] In one embodiment, at least one adsorbent bed comprises an alumina-based adsorbent for HCl and halogen removal, a ZnO-based adsorbent for HCl (and halogens) and HS removal, a Cu-based adsorbent for COS, CS2, and arsine removal, and an adsorbent for carbonyl removal.

[0036] In another embodiment, the absorption unit is a column comprising at least three mass transfer zone sections.

[0037] In yet another embodiment, the absorption unit is a column comprising at least four mass transfer zone sections.

[0038] In a further embodiment, the mass transfer zone sections are provided in separate columns.

[0039] In a further embodiment, hydrogen is taken from an external source.

[0040] In one embodiment, the captured hydrogen is derived from renewable sources and / or sources with low carbon intensity.

[0041] In another embodiment, the captured hydrogen is derived from water electrolysis with renewable or low carbon intensity electricity, biogas reforming or steam reforming, a low carbon intensity (CI) hydrogen source, or a low CI waste H2 source.

[0042] In certain embodiments, the purification unit or AGR comprises chilled methanol comprising a solvent.

[0043] In one embodiment, the pre-flashing pressure and temperature are adjusted to achieve a target CO2 content and recovery in the final clean syngas stream.

[0044] In a further embodiment, the balance syngas stream meets the stoichiometric requirements of a syngas conversion unit to produce fuels, chemicals, or Fischer-Tropsch products.

[0045] In another embodiment, the chemical or fuel is methanol or ethanol.

[0046] In one embodiment, the Fischer-Tropsch product is diesel, kerosene, jet fuel, or naphtha, or a mixture thereof.

[0047] In another embodiment, the clean syngas stream in the AGR achieves less than 100 ppbv, less than 10 ppbv, or alternatively less than 5 ppbv of HCN and NH3.

[0048] In one embodiment, the clean syngas stream in the AGR achieves less than 10 ppmv, less than 5 ppmv, less than 1 ppmv, or alternatively less than 0.1 ppmv of bound sulfur species.

[0049] In another embodiment, the clean syngas stream in the solid adsorbent bed achieves less than 10 ppbv, or alternatively less than 5 ppbv of sulfur species, halogen species, arsine, and / or metal carbonyls.

[0050] In one embodiment, the halogen species is HCl, HF, HBr, or a combination thereof.

[0051] In a further embodiment, the metal is Ni, Fe, or a combination thereof.

[0052] In another embodiment, the H2S concentration in the clean syngas stream is adjusted to achieve a specific desired concentration to meet the requirements of a downstream syngas conversion unit, while achieving low levels of HCN and / or NH3 concentrations.

[0053] In another embodiment, the H2S concentration in the clean syngas stream is maintained below 200 ppmv.

[0054] In another embodiment, the H2S concentration in the clean syngas stream is maintained below 100 ppmv.

[0055] In another embodiment, the method described herein further comprises a reverse water gas shift (RWGS) unit prior to the syngas conversion unit, in which a portion of the recovered CO2 is converted along with a portion of the captured H2 to generate additional carbon monoxide.

[0056] In a further embodiment, the additional CO product is mixed with a portion of the clean syngas to generate a CO-enhanced clean syngas.

[0057] In another embodiment, the CO2 is recycled to the carbonaceous feedstock gasification and / or reforming unit to reduce the H2 / CO ratio of the scrubbed syngas and increase the total CO yield and production, generating enhanced CO-scrubbed syngas and enhanced CO-clean syngas.

[0058] In one embodiment, the enhanced CO2 clean syngas is mixed with hydrogen to produce a balanced syngas stream, which meets the stoichiometric requirements of the syngas conversion unit.

[0059] In another embodiment, the syngas conversion unit converts H2+CO in situ and does not convert H2+CO2.

[0060] In another embodiment, the method described herein further comprises blending CO2 input from an external source of CO2 or another process effluent with the clean syngas stream along with an external source of hydrogen to produce a more carbon-enriched equilibrium syngas that meets the stoichiometry of the desired end products, thereby further increasing the production of the desired end products.

[0061] In one embodiment, the purification unit makes it possible to achieve a H2+CO recovery of more than 99% in the clean syngas.

[0062] In further embodiments, the scrubbed syngas is from the gasification and / or reforming of carbonaceous materials. Carbonaceous materials refer to any gas, liquid, or solid that contains "carbon" atoms. In most cases, these atoms may originate from plants or animals and their derivatives, or fossil fuels and their derivatives. Examples of materials include, but are not limited to, Municipal Solid Waste (MSW), Industrial, Commercial, and Institutional waste (IC&I), Construction and Demolition waste (C&D), any petroleum products, plastics, homogeneous and / or non-homogeneous biomass.

[0063] In a particular embodiment, the carbonaceous material comprises plastics, metals, inorganic salts, organic compounds, industrial waste, recycling plant waste, automobile fluff, municipal solid waste, ICI waste, C&D waste, refuse derived fuel (RDF), solid recovered fuel, sewage sludge, used electricity poles, railway sleepers, wood, tires, synthetic fibers, carpets, synthetic rubber, materials of fossil fuel origin, expanded polystyrene, polyfilm flock, building wood materials, or any combination thereof. The method according to the invention is in principle applicable to any carbon-based material. Here, it is not important whether the fuel is a biogenic or non-biogenic fuel.

[0064] In further embodiments, the carbonaceous material is biomass, biomass-rich waste, plastic-rich waste, or waste material.

[0065] In another embodiment, the carbonaceous material is waste plastic, waste rubber, or tire rich waste feedstock.

[0066] In one embodiment, an additional source of CO2 is captured in the purification unit by adding a CO2 capture and purification unit to produce a high quality and / or ultra-clean CO2 stream.

[0067] In a further embodiment, the CO2 capture and purification unit comprises a primary and / or secondary CO2 column, and medium quality CO2 is produced in the primary CO2 column and / or high quality CO2 is produced in the secondary CO2 column.

[0068] In another embodiment, some or all of the CO2-loaded solvent from the first recycle loop is used as a wash medium in the primary and / or secondary CO2 columns, the CO2 and sulfur species-loaded solvent from the second recycle loop is fed to the bottom of the primary CO2 column, the CO2 and sulfur species-loaded solvent from the bottom of the primary CO2 column is fed to the secondary CO2 column, and the concentrated sulfur species-loaded solvent from the bottom of the secondary CO2 column is fed to a stripping unit.

[0069] In one embodiment, the high quality CO2 is further processed with a solid adsorbent to produce ultra-high CO2 quality.

[0070] In one embodiment, the ultra-high CO2 quality is either blended into a clean syngas stream along with an external source of hydrogen to meet the stoichiometry of the desired end products, produce an equilibrium syngas that is further enriched in carbon, thereby further increasing the production of the desired end products, sold off-site, and / or sent for storage.

[0071] In another embodiment, the very high CO2 quality produced is sent along with additional captured hydrogen to a separate second syngas conversion unit that produces desired end by-products from the H2 and CO2.

[0072] In further embodiments, the by-product synthesis gas conversion unit is a methanol catalytic reactor, a Fischer-Tropsch reactor using an iron-based catalyst, or an ethanol reactor using a microbial biocatalyst.

[0073] In one embodiment, the first syngas conversion unit is capable of converting H2 and CO in situ to desired end products and is not capable of converting H2 and CO2 to desired end products.

[0074] In one embodiment, the purification unit comprises a stripping unit including a split-loaded stripper column having at least top and bottom mass transfer zone sections, where nitrogen species-laden methanol is fed to the top of the stripper column and above the top mass transfer zone, and sulfur species-laden methanol is fed to the middle of the stripper column between the top and bottom mass transfer zone sections.

[0075] Reference is now made to the accompanying drawings, in which: [Brief description of the drawings]

[0076] [Figure 1] 1 shows a flow diagram of a method described herein, according to one embodiment.

[0077] [Diagram 2] FIG. 1 shows a flow diagram of the method described herein according to one embodiment, including details of the purification unit.

[0078] [Diagram 3] FIG. 1 shows a flow diagram of the method described herein according to one embodiment, including details of the purification unit and options for achieving high removal efficiency of HCN and / or NH3.

[0079] [Figure 4] FIG. 1 shows a flow diagram of the method described herein according to one embodiment, including details of the purification unit and the option to achieve high HCN and / or NH3 removal efficiency with a second stripping unit.

[0080] [Diagram 5] A flow diagram of the method described herein according to one embodiment is shown, including details of the CO2 capture and purification unit and the option to capture additional ultra-clean high-quality CO2 within the AGR. Figure 5 also shows a configuration in which a fourth mass transfer zone for HCN / NH3 removal is installed in a separate column.

[0081] [Figure 6] FIG. 1 shows a flow diagram of the method described herein, according to one embodiment, including details of split-load nitrogen and sulfur species stripping units and options for further improving the efficiency of the AGR. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0082] In accordance with the present disclosure, methods are provided for optimizing syngas carbon utilization, syngas purity, and syngas conversion to subsequent downstream syngas conversion units.

[0083] Methods are provided for maximizing the yield of syngas-derived products (e.g., methanol) from gasification and / or reforming of variable carbonaceous feedstock compositions when an external source of hydrogen, preferably green, renewable or low carbon intensity hydrogen, is available.

[0084] Rather than shifting excess CO to H2 in plants using carbonaceous feedstocks, it is disclosed that an external source of hydrogen can be introduced into the plant and combined with the plant CO rich syngas to re-equilibrate the overall plant H2 / CO ratio to that required according to the ratio resulting from the stoichiometric reaction of the desired end products.

[0085] It is also known that several chemicals and fuels can be produced not only from the reaction of H2 with CO, but also from the reaction of H2 with CO2. One such product is methanol, but also Fischer-Tropsch using iron-based catalysts and ethanol using microbial biocatalysts.

[0086] In most existing syngas-to-methanol plants, methanol is produced in a catalytic reactor by the following chemical reaction: CO+2H2⇔CH3OH (2) CO2+H2⇔CO+H2O (3) CO2+3H2⇔CH3OH+H2O (4)

[0087] It is understood and required that a minimum amount of CO2 is needed in the syngas to the methanol reactor to obtain high methanol productivity and higher dry basis methanol purity (i.e. kg methanol / hr per kg catalyst).

[0088] A typical modern syngas to methanol plant prepares make-up syngas that is sent to a methanol reactor loop. To achieve high carbon efficiency (CO and CO2 conversion to methanol), the make-up syngas must be balanced; i.e., any large excess of CO, CO2, or H2 can result in loss of valuable molecules via the reactor loop purge gas stream, since inevitably some non-condensable gases (usually N2, CH4, etc.) acting as inert / diluent gases must be purged from the system.

[0089] Fully equilibrated syngas may have a stoichiometric ratio or number (SN) of 2.0, which would theoretically result in complete conversion of H2, CO, and CO2 to methanol according to the three reactions above. Typically, a slight excess of H2 is recommended, which would result in an SN of slightly more than 2.

number

[0090] Modern methanol reactor designs and catalysts can also convert CO2 along with H2 to methanol, so carbonaceous-rich feedstock gasification and / or reforming plants that include an external source of hydrogen may benefit from new plant designs as proposed herein that maximize CO and CO2 capture from carbonaceous feedstocks to achieve higher methanol yields.

[0091] Table 1 shows the range of CO2 concentrations in the make-up gas at a constant stoichiometric number (SN) of 2.04, ranging from no CO2 (all methanol present via equation 2) to no CO (all methanol present via final reaction 4). Thus, methanol can be produced from CO-rich syngas to CO2-rich syngas and any proportion in between. [Table 1]

[0092] One of the challenges of waste, plastic rich waste, biomass, and / or biomass rich gasification and / or reforming is the variability of the feedstock gasification / reformation composition over time (week to week, month to month variations due to the variable nature of such feedstocks), which impacts the H2, CO, CO2 yields (flow rates) and contaminant concentrations in the produced scrubbed syngas, i.e., "various scrubbed syngas sources." In this case, downstream unit designs, especially purification units, must have the ability to manage the variable syngas composition while achieving targeted contaminant removal, while maximizing CO and CO2 capture for maximum methanol or biofuel production.

[0093] In one embodiment, the contaminants include, but are not limited to, sulfur species such as H2S, COS, and / or CS2, nitrogen species such as HCN, NH3, and / or amines, water, and aromatics such as benzene, toluene, and xylene. Nitrogen (N2) is not a contaminant.

[0094] In a further embodiment, the purification unit is an acid gas removal unit (AGR) that includes selective solvents for absorbing CO, sulfur contaminants (e.g., H2S, COS, and / or CS2), and nitrogen contaminants (e.g., HCN, NH3, and / or amines).

[0095] As described herein, the methods provided for methanol production from gasification and / or reforming of carbonaceous feedstocks also apply to other products that use methanol as an intermediate and / or directly from synthesis gas and / or other intermediates.

[0096] In one embodiment, the carbonaceous material / feedstock comprises plastics, metals, inorganic salts, organic compounds, industrial waste, recycling plant waste, automobile fluff, municipal solid waste, ICI waste, C&D waste, refuse derived fuel (RDF), solid recovered fuel, sewage sludge, used utility poles, railway sleepers, wood, tires, synthetic fibers, carpet, synthetic rubber, fossil fuel derived materials, expanded polystyrene, polyfilm flock, building wood materials, or any combination thereof. Thus, encompassed are methods for producing methanol from gasification and / or reforming of carbonaceous feedstocks, such as biomass, biomass rich waste, plastic rich waste, and / or waste materials.

[0097] As shown in FIG. 1, a method is provided herein that includes maximizing hydrogen, carbon monoxide, and carbon dioxide recovery in the purification unit 11. First, the cleaned syngas 10 is fed to the purification unit 11 to optimize CO2 recovery in the purification unit 11 and maximize the CO2 content in the clean syngas 40 leaving the purification unit 11. The captured hydrogen 42 is injected into the clean syngas 40 to prepare a balanced make-up syngas 44 and fed to a catalytic syngas conversion unit 60 to produce the desired end products 61. A non-combustible CO2-rich stream 32 is generated, which can be used as an inert gas upstream of the plant. In addition, in one embodiment, a high-quality CO2 stream or an ultra-clean CO2 stream (88) is generated and can be optionally mixed with the clean syngas stream 40 together with an external source of hydrogen 42 to produce a further carbon-enriched balanced syngas 44 that meets the stoichiometric ratio target of the desired end products, thereby further increasing the production of the desired end products (see FIG. 5). Additionally, in another embodiment, the ultra-clean CO2 can be sold off-site or sent for storage (i.e., CCS) (stream 89). The methods described herein allow for the removal of scrubbed syngas contaminants 29 in the purification unit 11.

[0098] Because the yield of H2+CO relative to CO2 in various scrubbed syngas sources can vary over time, the AGR design and downstream syngas conversion units must be designed to manage a range of syngas compositions and have the ability to accommodate such syngas yield variations while always maximizing production and H2 capture capacity within the plant.

[0099] Syngas yield refers to the amount of H2, CO, and CO2 produced by a gasification / reforming unit per input amount of carbonaceous feedstock fed to the gasification / reforming unit. Syngas yield variability means that the total syngas flow rate and composition, and therefore the individual H2, CO, and CO2 flow rates, can vary over time (week-to-week, month-to-month variations due to the variable nature of such feedstocks).

[0100] Additionally, downstream of the gasifier / reformer there are often steps of quenching the hot syngas, heat recovery, and washing using water as a washing medium. In this case, the wet-scrubbed syngas is fed to the AGR with or without a compression step. Hydrolysis of COS to H2S units may also be included prior to the AGR, which also typically catalyzes the hydrolysis of HCN to NH3.

[0101] Thus, a novel AGR design is provided for processing the scrubbed syngas through an acid gas removal unit specifically designed to manage the varying scrubbed syngas yield and split it into the following different gas streams: (i) a clean syngas stream having low sulfur contaminant concentrations (such as, but not limited to, H2S, COS, and / or CS2), and optionally, low nitrogen contaminant concentrations (such as, but not limited to, HCN and / or NH3); (ii) a rich syngas pollutant loaded gas stream (having sulfur species and / or HCN / NH3); (iii) a low quality CO2 stream rich in H2 and CO (recirculated to the syngas inlet of the AGR absorption column); (iv) a non-combustible rich CO2 stream (medium quality CO2), and (v) Optionally, a high quality and / or ultra-clean CO2 stream.

[0102] The novel AGR design has operating handles that allow for maximizing H2 and CO recovery while adjusting CO2 recovery using variable inlet scrubbed syngas composition to maximize methanol production.

[0103] As shown in Figure 2, the scrubbed syngas 10 is first fed to an absorption column 12 that uses a selective solvent for CO and H2S and other sulfur species. Such a solvent can be, for example, but is not limited to, chilled methanol.

[0104] The absorption column 12 has at least three mass transfer zone sections (e.g., but not limited to, trays, random packing, and / or structured packing, i.e., top section 18, middle section 16, and bottom section 14). The three mass transfer zone sections can be located in one single column 12 having three sections, or in two or three separate columns.

[0105] The loaded solvent, still containing H2 and CO, passes through at least two recirculation loops around the absorber: a first loop 20 and a second loop 22. The second loop 22 is taken from the bottom section 14 of the absorption column 12, and the first loop 20 is taken from the middle section 16 of the absorption column 12.

[0106] Both loops taking the solvent from the absorber section are pre-flashed at intermediate pressure (21, 23) to recover the valuable H2 and CO absorbed in the solvent, thereby generating two H2 and CO rich CO2 streams, one for the second loop 22 (26) and one for the first loop 20, which are then combined and recycled in the syngas feed 10 upstream of the absorption column 12. The recovered valuable H2 and CO have another chance to pass through and exit the absorption column as part of the clean syngas 40 sent to the downstream catalytic reactor unit (60). Such pre-flashing and recycling allows for H2+CO recovery of more than 99% in the entire AGR unit (i.e., recovery = amount of H2 and CO in stream 40 divided by amount of H2 and CO in the inlet scrubbed syngas stream 10).

[0107] As a second step, the first loop solvent 20 is then further flashed (30) at lower pressure to generate a non-flammable CO2-rich stream 32 that can be used as an upstream inert gas in the plant. Alternatively, this CO2-rich stream can be recovered for carbon capture and storage (CCS) and / or to generate saleable commercial CO2, with or without additional processing. The clean solvent is recycled (33) to the absorption column 12.

[0108] As a second step, the pre-flashed second loop solvent 24 is then fed to a thermal stripping unit 25 for regeneration to remove absorbed sulfur contaminants, thereby producing a sulfur-rich contaminant gas stream 29 and a clean regenerated solvent stream that is recycled (27) to the top section 18 of the adsorber 12. The thermal stripping unit 25 can be a column with trays or packing equipped with either or both of a reboiler and a condenser.

[0109] As shown in Figure 3, if necessary, the purification unit can be fitted with a third recycle loop (46) to increase the NH3 and HCN removal efficiency. A fourth mass transfer zone section 45 can be added to the main absorption column 12 (Figure 3) or installed in a separate column (Figure 5). The third loop solvent 46 is pre-flashed at an intermediate pressure 53 to recover valuable H2 and CO absorbed in the solvent, thereby producing a H2 and CO rich CO2 stream 47, which is then combined and recycled in the syngas feed 10 upstream of the absorption column 12.

[0110] The pre-flashed third loop solvent 48 is then fed to the thermal stripping unit 25 for regeneration to remove the absorbed nitrogen contaminants, thereby producing a rich sulfur species, NH3, and HCN gas stream 29.

[0111] Alternatively, as shown in FIG. 4, the pre-flushed third loop solvent 48 can be fed to a separate thermal stripping unit 52 to remove absorbed nitrogen contaminants, thereby producing a rich NH and HCN gas stream 51 and clean solvent 49.

[0112] Alternatively, the solvent supplied to the fourth mass transfer zone section 45 may be partially or completely supplied from the slip stream 54 from the first solvent loop 20, as shown in Figures 3 and 4. In this configuration, the second solvent loop 22 may therefore be either a full or partial liquid draw from the third mass transfer zone 14. If the fourth mass transfer zone section 45 is placed in a separate column, as in Figure 5, The scrubbed synthesis gas 10 is fed to the bottom of the mass transfer zone section (53), the solvent stream 54 taken from the first recirculation loop 20 is fed to the top of the fourth mass transfer zone section 45; and · The pretreated gas 41 exiting the top of the fourth mass transfer zone section 45 is fed to the bottom of the absorber column 12 (bottom of the third mass transfer zone 14).

[0113] If low levels of nitrogen species contaminants are present in the scrubbed syngas, thus requiring a lower third loop flow rate, the recoverable H2+CO and CO2 in the pre-flash step 53 would also be lower. Thus, the extra project CAPEX for the installation step 53 may not be justified. In such a case, the absorbed H2+CO and CO2 in the third solvent loop 46 would be lost in the stripper effluent stream 29 (FIG. 3) or 51 (FIG. 4).

[0114] Clean regenerated solvent 49 and 27 is obtained from stripping unit 52 (FIG. 4) and / or stripping unit 25 (FIGS. 2 and 3), respectively, and then cooled before being fed to the top section 18 of adsorber 12, thereby removing final traces of sulfur and / or nitrogen contaminants from the syngas, thereby producing a clean syngas stream 40 having low sulfur contaminant concentrations (FIGS. 2, 3, and 4) and / or very low nitrogen contaminant concentrations (FIGS. 3 and 4).

[0115] If necessary, to protect downstream syngas conversion catalysts, the clean syngas stream 40 is further treated (before or after H2 uptake addition 42) in a solid adsorbent bed 36 that includes single or multiple adsorbent beds in one or more parallel or / and series vessels. The adsorbents may include alumina-based adsorbents for removal of HCl and halogens, ZnO-based adsorbents for removal of HCl, halogens, and H2S, Cu-based adsorbents for removal of COS, CS2, and arsine, adsorbents for carbonyl (Fe or Ni, or other) removal, and / or adsorbents for removal of HCN and / or NH3.

[0116] The clean syngas stream 40 is mixed with an external source of hydrogen 42 to produce an equilibrium syngas that meets the stoichiometric requirements of the syngas conversion unit, thereby producing an optimized carbon-captured equilibrium syngas 44 .

[0117] The improved methods of the present disclosure allow for the production of an optimized carbon-recovered equilibrium syngas that allows for an increase in the overall carbon-scrubbed syngas and carbon feedstock conversion to final desired products by more than 65% (compared to the conventional approach of removing excess CO2 by shifting the excess CO with a water gas shift (WGS)) and even more than 140% depending on the initial scrubbed syngas composition (see Tables 2 and 3). [Table 2] [Table 3]

[0118] For methanol production, the equilibrium syngas may have an optimum stoichiometric ratio (SN) slightly above 2, as explained above, but may also be operated at lower or higher stoichiometric ratios. Other syngas conversion units or technologies to obtain different end products may have different target stoichiometric ratio formulas and / or values.

[0119] In one embodiment, the captured hydrogen / external source of hydrogen 42 is derived from a renewable source and / or a source with low carbon intensity.

[0120] In additional embodiments, the source 42 of captured hydrogen is derived from water electrolysis with renewable or low carbon intensity (CI) electricity, biogas reforming or steam reforming, a low carbon intensity (CI) hydrogen source, or a low CI waste H2 source.

[0121] Finally, the optimized carbon-recovered equilibrium syngas 44 is fed to a syngas conversion unit 60 (syngas conversion reaction system) to produce fuels and / or chemicals with optimized carbon content as desired end products (61).

[0122] Considering that the downstream syngas conversion unit 60 is designed at maximum capacity and / or the H2 intake 42 also has a maximum supply capacity, in order to maximize plant profitability at various scrubbed syngas compositions and yields, design and operating handles must be provided to always maximize biofuel production and profitability.

[0123] At lower H2+CO yields in the scrubbed syngas, more H2 is required for conversion of CO2 to methanol per reaction 3, so a higher AGR CO2 capture rate would be required to keep the plant at its maximum methanol capacity and maximum uptake hydrogen availability.

[0124] With higher H2+CO yields in the scrubbed syngas, lower AGR CO2 capture rates would be required to keep the plant at its maximum methanol capacity while minimizing H2 uptake and therefore variable operating costs.

[0125] In the provided AGR design, the AGR includes the following design and operation handles to optimize CO2 capture and keep the plant at its maximum methanol capacity and optimal hydrogen usage:

[0126] The flow rates and / or temperatures of the first loop 20 and the second loop 22 are adjusted to achieve a target CO2 content and low reduced sulfur content in the final clean syngas stream (40); and / or

[0127] The pre-flash pressure of the first and / or second loop (21 and 23 respectively) is further optimized and the generated CO2 stream (28 and 26 respectively) is recirculated upstream of the AGR to maximize the CO2 capture in the final clean syngas stream (40).

[0128] The pressure of the low pressure flash 30 in the first loop 20 can be adjusted to optimize CO2 capture to achieve the exact amount of non-combustible rich CO2 stream 32 required, thus balancing the CO2 in the clean syngas 40 exiting the AGR 12.

[0129] If high HCN and / or NH3 removal levels are required in the configurations of Figures 3 or 4, the AGR design further includes the following design and operating handles to optimize CO2 capture. - the flow rate and / or temperature of the third recycle loop 46 is adjusted to achieve a target CO content and low reduced nitrogen species content in the final clean syngas stream (40); and / or The pre-flash pressure in the third loop (53) is further optimized and the generated CO2 stream (47) is recirculated upstream of the AGR to maximize the CO2 capture in the final clean syngas stream (40).

[0130] As illustrated herein, synthesis gas generation for methanol production is used as an example. However, it can be applied to any synthesis gas conversion process to chemicals and fuels that can be produced from H2 and CO2 in addition to H2 and CO2, such as, but not limited to, Fischer-Tropsch using iron-based catalysts and ethanol using microbial biocatalysts. Desired Fischer-Tropsch products include fuels such as diesel, kerosene / jet fuel, and / or naphtha after purification or upgrading of the crude Fischer-Tropsch product, but also waxes, base oils, and the like.

[0131] Methanol can also be used as an intermediate product. When initially produced, it can be further converted to olefins (propylene and ethylene), formaldehyde, gasoline, naphtha, kerosene, aviation fuel, and / or diesel. Ethanol can be used as a fuel or as an intermediate product for the production of ethylene, for example, by dehydration.

[0132] In addition, the objective of maximizing syngas-derived product yields with syngas CO capture and external H uptake from biomass-rich feedstocks is also applicable to any carbonaceous feedstock with the objective of maximizing yield and production and / or reducing CO greenhouse gas (GHG) emissions. For example, chemical recycling of plastic-rich waste, waste rubber, tires, etc. via gasification methods may also benefit from this novel AGR design by maximizing the conversion of total feedstock carbon to desired end products, thus minimizing plant CO GHG emissions. More specifically, olefin production from methanol or ethanol can be used for plastic production, thus closing the circulation loop when using plastic-rich waste as a gasification feedstock.

[0133] In one embodiment, the clean syngas stream 40 at the outlet of the AGR absorber achieves less than 100 ppbv, less than 10 ppbv, or alternatively less than 5 ppbv of HCN and NH3.

[0134] In another embodiment, the clean syngas stream 40 at the outlet of the AGR absorber achieves less than 10 ppmv, less than 5 ppmv, less than 1 ppmv, or alternatively less than 0.1 ppmv of combined sulfur species.

[0135] In another embodiment, the clean syngas stream at the outlet of the solid adsorbent bed 36 achieves less than 10 ppbv, or alternatively less than 5 ppbv, of sulfur species, halogen species (e.g., HCl, HF, HBr, etc.), arsine, and / or metal (e.g., Ni and / or Fe) carbonyls.

[0136] In another embodiment, the H2S concentration in the clean syngas stream 40 at the outlet of the AGR absorber can be adjusted to achieve a certain higher desired concentration to meet the requirements of the downstream syngas conversion unit, while achieving low levels of HCN and / or NH3. This functionality is particularly interesting when using microbial syngas conversion techniques (60) where some H2S is required to maintain microbial activity, but HCN is a known poison. In such cases, the H2S concentration in the clean syngas stream 40 at the outlet of the AGR absorber can be maintained below 200 ppmv, alternatively below 100 ppmv, while achieving low levels of HCN and / or NH3. Reducing the H2S removal requirement reduces the flow rate and / or stripping unit (25) load of the second recirculation loop 22, reduces the inherent loss of CO2 through the rich sulfur pollutant gas stream 29, thus increasing the CO2 recovery and concentration in the clean syngas 40, and allows for the production of fuels and / or chemicals with a more optimized carbon content as the desired end product (61).

[0137] In another embodiment, this novel AGR design can also be used to completely remove CO2 from the scrubbed syngas 10 to produce an ultra-low CO2 concentration clean syngas 40 or to achieve a specific lower CO2 concentration in the clean syngas 40. For such purposes, the pre-flash pressure of the recycle loop is optimized (and recycled to the absorber) to reduce CO2 flash while still achieving the target H2 and CO recovery. The recycle loop flow rate is increased to achieve higher CO2 removal. Such flexible designs are particularly interesting for plant designs where H2 uptake is not available and / or for syngas conversion technologies where CO2+H2 cannot be used to make the desired end products.

[0138] In another embodiment, CO2 input from an external source of CO2 or another process effluent can be mixed with the clean syngas stream 40 along with an external source of hydrogen 42 to produce a more carbon enriched equilibrium syngas 44 that meets the stoichiometric ratio targets of the desired end products, thereby further increasing the production of the desired end products. The flow of the external source of hydrogen (42) must be increased accordingly. Alternatively, if this additional CO2 source requires cleaning, it can be fed to the AGR inlet.

[0139] Such a source of CO from another part of the process may be uncaptured CO lost in the rich sulfur stream (29) and / or the nitrogen species rich stream (51). Therefore, to recover CO from this waste stream for catalytic synthesis, additional processing units may be required to reduce contaminants to ultra-low levels. Such additional processing units include, but are not limited to, additional absorption / stripping techniques, solid sorbent techniques, etc.

[0140] In another embodiment, additional ultra-clean, high quality CO2 can be captured by adding a CO2 capture and purification unit (99) within the AGR, as shown in Figure 5.

[0141] In such a configuration, rather than being recycled to the AGR absorber (12), a portion (35) is sent to the top of a primary CO2 column (70) that includes at least one mass transfer zone. In addition, the CO2 and sulfur species loaded methanol (24) is sent to the bottom of the primary CO2 column (70). In the primary CO2 column, the low sulfur CO2 loaded methanol 35 acts as a scrubbing medium to retain the sulfur species down the column while recovering a second medium quality CO2 (71) from both loaded methanol streams. The primary CO2 column also removes additional non-condensable gases (e.g., CO and H2) from the bottom of the column, which further contributes to achieving ultra-low CO specifications in the high quality CO2 (stream 80).

[0142] The first captured intermediate quality CO2 stream is in fact the aforementioned stream 32. Both intermediate quality CO2 streams (32 and 71) are combined into stream 82 which meets the aforementioned non-flammable quality criteria. Optionally, they are compressed in compressor (83) for use as an inert gas in the plant front-end supply system or for other uses, as previously described.

[0143] The bottom CO2 and sulfur species loaded methanol (72) is fed between two mass transfer zones (74 and 75) of a secondary CO2 column (73). The remainder of the CO2 loaded methanol (34) is fed to the top of that column to act as a scrubbing medium to retain sulfur species and other contaminants down the secondary CO2 column (73), while recovering a high quality CO2 stream (80) from both the CO2 and sulfur species loaded methanol (72) and the remainder of the CO2 loaded methanol (34). At the bottom of the secondary CO2 column (73), concentrated sulfur species loaded methanol (76) is sent to a CO2 flash unit (77) to maximize CO2 recovery from the bottom concentrated sulfur species loaded methanol (76).

[0144] The CO2 flash unit (77) comprises a combination of low pressure flash with flash gas recompression and / or heat assisted pressurized flash. The flashed CO2 rich stream (78) is returned to the bottom of the secondary CO2 column (73).

[0145] Concentrated sulfur species loaded methanol (79) is obtained from the CO2 flash unit (77) and then sent to the AGR stripping unit (25). The nitrogen species loaded methanol (48) can be sent directly to the AGR stripping unit (25) or incorporated into the CO2 capture and purification unit 99 to recover its small CO2 content. The AGR stripping unit 25 regenerates both loaded methanol to dilute methanol (27), which is recycled to the top of the AGR absorber (12) section (18) as previously described. The resulting AGR sulfur and / or nitrogen species waste gas stream (29) is thus more concentrated in sulfur and nitrogen species, and therefore results in less carbon (as CO2) loss from the process.

[0146] The recovered high quality CO2 stream (80) is then compressed to higher pressure in compressor (81) if necessary. Depending on the required high quality CO2 target specifications, it can then be treated in a solid phase absorbent unit (90) to remove residual contaminants to ultra-low ppm or ppb levels, as previously described for the clean syngas guard bed (36). The resulting ultra-clean CO2 stream (87, 88) can then be mixed with the clean syngas stream 40 along with an external source of hydrogen 42 to produce a further carbon-enriched equilibrium syngas 44 that meets the stoichiometric ratio targets of the desired end products, thereby further increasing the production of the desired end products. As previously described, the flow of the external source of hydrogen (42) must be increased accordingly.

[0147] Table 4 below shows that the additional CO2 capture and yield increases with this additional functionality to the AGR. [Table 4]

[0148] Certainly, such additional CO2 capture and increased desired product yields require the availability of additional captured hydrogen (42). For a variety of reasons, particular project and plant locations may limit access to captured hydrogen. Thus, one important feature of the present invention is that each project may decide to include all or only some of the features described herein to achieve the project's particular requirements and minimize project profitability and / or environmental footprint.

[0149] If a lower quality of CO2 is required, the flash step 30 can be omitted and therefore the first loop 31 can be split into two (34 and 35) instead of stream 33 to feed the primary (70) and secondary (73) CO2 columns. In that configuration, all intermediate CO2 qualities can be fed from the primary CO2 column via stream 71. Alternatively, if a lower CO2 quality is required, the primary CO2 column can be omitted. In that configuration, the CO2-loaded methanol (33) is fed directly to the top of the secondary CO2 column (73) and the CO2- and sulfur species-loaded methanol (24) is fed directly between the two mass transfer zones (74 and 75) of the secondary CO2 column (73).

[0150] In another embodiment, if the available hydrogen supply is limited, or if the desired end product synthesis catalyst and unit (60) is not capable of converting the captured ultra-clean CO2 (87) into additional desired products, the ultra-clean CO2 can be sold off-site or sent for storage (i.e., CCS) (Stream 89).

[0151] Alternatively, if the desired end product synthesis catalyst and unit (60) is not capable of converting the captured ultra-clean CO2 (87) to additional desired products, the ultra-clean CO2 can be sent to a methanol reactor (stream 89) along with additional captured hydrogen to co-produce methanol in the plant. An alternative to methanol co-production is any technology capable of converting CO2 + H2 to the desired end products, as previously discussed.

[0152] In another embodiment, any excess (85) of medium quality CO2 (84) can be mixed with high quality CO2 (86) to further maximize yield and production of desired end products.

[0153] When a CO2 capture and purification unit (99) is included in the AGR configuration, the AGR design further includes the following design and operation handles to optimize CO2 capture from the variable scrubbed syngas source: The flow rates and / or temperatures of the first loop 20 and the second loop 22 are adjusted to achieve a target CO2 content and low sulfur content in the final clean syngas stream (40) and / or a target recovery rate of high purity CO2 (87). The pre-flush pressure of the first and / or second loop (21 and 23 respectively) is further optimized and the generated CO2 stream (28 and 26 respectively) is recirculated upstream of the AGR to balance the desired CO2 recovery in the final clean syngas stream (40) against the recovery of high purity and / or ultra clean CO2 (87). The pressure of the first loop 20 and the low pressure flash 30 can be used to reduce the CO content in the high quality CO2 (80). The pressure and / or temperature of the CO2 flash unit (77) can be adjusted to achieve the desired high purity CO2 (87).

[0154] In another embodiment, the AGR stripping unit (25) is not a standard configuration stripper, but rather a split-load nitrogen and sulfur species stripping unit design, where the combined contaminant-laden solvent is sent to the top of the stripper and the contaminants are stripped as the solvent flows down to the bottom of the stripper, generating regenerated solvent at the bottom of the stripper.

[0155] The split-loading design option (Figure 6) of the AGR stripping unit (25) allows for further improvement in the overall energy efficiency of the entire AGR unit, as shown in Table 5 below. [Table 5]

[0156] In the split-loading design option, the stripper column (100) has at least two mass transfer zone sections (101 and 102). Nitrogen species-laden methanol (48) is fed to the top of the stripper column and above the top mass transfer zone (102), while sulfur species-laden methanol (79) is fed to the middle of the stripper column (100), between the top (102) and bottom (101) mass transfer zone sections. Thermal energy (114) is fed to the stripper column (100) through a stripper reboiler (112), which vaporizes a portion (111) of the column bottom product (110) to generate steam boilup (113), which is returned to the bottom of the stripper column (100). The stripper column (100) also includes a condenser (104) for cooling and condensing the methanol vapor in the column overhead vapor (103). At the outlet of the condenser (104), stream 105 contains condensed methanol and non-condensable tail gases, which are separated in reflux drum (106) into liquid reflux (109) required for column operation and sulfur and / or nitrogen species tail gases (29). The regenerated solvent (27) at the bottom of the stripper column (100) is then recycled to the top mass transfer zone section (18) of the absorber column (12), as previously described.

[0157] In one embodiment, if the scrubbed syngas (10) contains significant concentrations of aromatic compounds such as benzene and toluene, a liquid purge (108) can be extracted from the reflux vapor (109) to minimize the accumulation of these aromatic compounds in the AGR loop.

[0158] In one embodiment, this novel AGR design can also be integrated with a process incorporating a reverse water gas shift (RWGS) unit, as described in U.S. Patent Application No. 63 / 185,482, the contents of which are incorporated herein in their entirety, to convert the captured CO along with the captured H to generate additional carbon monoxide prior to the syngas conversion unit. The additional CO product is mixed with the remainder of the clean syngas to generate a CO-enhanced clean syngas.

[0159] In another embodiment, as described in U.S. Patent Application Serial No. 63 / 185,482, the captured CO2 of this novel AGR design is recycled to the carbonaceous feedstock gasification and / or reforming unit to reduce the H2 / CO ratio of the reformed syngas and increase the total CO yield and production, thus generating enhanced CO scrubbed syngas and enhanced CO clean syngas at the outlet of the AGR.

[0160] In both cases, the enhanced CO clean syngas is mixed with hydrogen to produce an equilibrium syngas stream that meets the stoichiometric ratio requirements of the syngas conversion unit. Such an option is advantageous when the syngas conversion unit can convert only H2+CO to the desired products in situ, but not H2+CO2 to the desired products, for example, but not limited to, Fischer-Tropsch units or technologies using cobalt-based catalysts, or ethanol production technologies using a methanol carbonylation pathway.

[0161] Although the present disclosure has been described with particular reference to the illustrated embodiments, it will be understood that numerous modifications thereto will become apparent to those skilled in the art. Accordingly, the above description and accompanying drawings should be interpreted as illustrative and not in a limiting sense. For the sake of simplicity, some secondary details such as pumps, heat exchangers, some compressors, etc. have been omitted.

[0162] While the disclosure has been described in relation to particular embodiments thereof, it will be understood that it is capable of further modifications, and this application is intended to cover any variations, uses, or adaptations thereof, including such departures as are known or customarily made in the art that may be applied to the essential features described hereinabove, and which fall within the scope of the appended claims.

Claims

1. 1. A method for optimizing syngas carbon utilization, syngas purity for subsequent syngas conversion from a scrubbed syngas source to a downstream syngas conversion unit, comprising: a) feeding the scrubbed syngas to a purification unit comprising at least one absorption unit to remove CO from the scrubbed syngas ２ a clean synthesis gas stream and CO ２ generating a rich stream, wherein the purification unit is an acid gas removal unit (AGR), and in the AGR: - CO 2 and sulfur species are absorbed from the washed syngas in an absorption unit using the selective solvent to produce a loaded solvent and washed syngas stream; - the loaded solvent is removed through at least one recirculation loop, - the loaded solvent is pre-flashed at an intermediate pressure to recover absorbed H 2 and CO, producing the CO 2 -rich stream and a flashed solvent stream rich in H 2 and CO; - the flashed solvent is flashed at a lower pressure to recover CO 2 and generate a non-combustible CO 2 rich stream and a second flashed solvent; the second flashed solvent is stripped in a first stripping unit to remove the sulfur species and produce a sulfur-rich species stream and a clean solvent that is recycled to the absorption unit; Steps and b) mixing the clean syngas stream with hydrogen to produce an equilibrium syngas stream, wherein the equilibrium syngas stream meets the stoichiometric requirements of the syngas conversion unit; and c) feeding the balanced syngas stream to the syngas conversion unit; A method comprising:

2. The method of claim 1 , wherein the at least one absorption unit further removes sulfur species and produces an additional sulfur species-rich stream.

3. The sulfur species is H ２ S, COS, CS ２ or a combination thereof.

4. The method of any one of claims 1 to 3, wherein the at least one absorption unit further removes nitrogen contaminant species and produces an additional nitrogen contaminant-rich stream.

5. The scrubbed synthesis gas source is 25 to 45 mole % H ２ , 30 to 65 mol% CO, and 6 to 40 mol% CO ２ The method according to any one of claims 1 to 3, comprising:

6. The composition of the clean syngas stream is 30% to 50 mol % H ２ , 40-68 mol% CO, and 0-25 mol% CO ２ The method according to any one of claims 1 to 3, comprising:

7. The CO ２ recycling the rich stream for use as an inert gas; ２ exporting the rich stream for carbon capture and storage (CCS), and / or ２ Salable commercial CO from Richstream ２ The method of any one of claims 1 to 3, further comprising the step of generating:

8. a first portion of the loaded solvent is removed through a first recirculation loop, and a second portion of the loaded solvent is removed through a second recirculation loop; - pre-flashing the first portion of the loaded solvent at an intermediate pressure to remove the H ２ and recovering the CO and H ２ and a CO-rich first CO ２ and a first flashed solvent, and pre-flashing the second portion of the loaded solvent at an intermediate pressure to remove H2 contained in the loaded solvent. ２ and CO are recovered, and H ２ and a CO-rich second CO ２ a second flashed solvent; - flashing the first flashed solvent at a lower pressure to produce non-flammable CO ２ generating a rich stream and a clean solvent recycled to the absorption unit; -H ２ and the first CO rich ２ stream and the second CO ２ recirculating the stream into the scrubbed synthesis gas stream upstream of said absorption unit; stripping the second solvent to remove sulfur species in a first stripping unit to produce a sulfur-rich species stream and a clean solvent that is recycled to the absorption unit; The method of claim 1.

9. 4. The method of any one of claims 1 to 3, wherein the selective solvent in the purification unit further removes the sulfur and nitrogen species to produce a sulfur and nitrogen species-rich stream.

10. a first portion of the loaded solvent is removed through a first recirculation loop, a second portion of the loaded solvent is removed through a second recirculation loop, and a third portion of the loaded solvent is removed through a third recirculation loop; The first portion of the loaded solvent is pre-flashed at an intermediate pressure to remove the H2 contained in the loaded solvent. ２ and recovering the CO and H ２ and a CO-rich first CO ２ and a first flashed solvent, and pre-flashing the second portion of the loaded solvent at an intermediate pressure to remove H2 contained in the loaded solvent. ２ and CO are recovered, and H ２ and a CO-rich second CO ２ and a second flashed solvent, and optionally pre-flashing the third portion of the loaded solvent at an intermediate pressure to remove the H2 contained in the loaded solvent. ２ and recovering the CO and H ２ and a CO-rich third CO ２ a third flashed solvent; The first flashed solvent is flashed at a lower pressure to produce a non-flammable CO ２ generating a rich stream and a clean solvent recycled to the absorption unit; H ２ and the first CO rich ２ the second CO ２ and optionally said third CO ２ recirculating the stream into the scrubbed synthesis gas stream upstream of said absorption unit; stripping the second flashed solvent and the third flashed solvent, or unflashed solvent, in a stripping unit to remove the sulfur and nitrogen species to produce a rich sulfur and nitrogen species stream and a clean solvent that is recycled to the absorption unit; 10. The method of claim 9.

11. 11. The method of claim 10, wherein the third flashed solvent is stripped in a second separate stripping unit.

12. 9. The method of claim 1, wherein the first stripping unit and / or the second stripping unit is a thermal stripper that removes the sulfur species and / or the nitrogen species to produce a sulfur-rich gas stream and / or a nitrogen-rich gas stream, and a clean solvent, and the clean solvent is recycled to the at least one absorption unit.

13. The method of claim 12, wherein the loop flow rate, temperature, and / or pressure in the pre-flashing step is adjusted to a target CO 2 concentration in the final clean syngas stream. ２ The method of any one of claims 1 to 3 or 8, wherein the content is adjusted to achieve the above.

14. The sulfur species is H ２ S, COS, CS ２ or a combination thereof.

15. Nitrogen contaminant species include HCN, NH ３ , an amine, or a combination thereof.

16. 9. The method of any one of claims 1 to 3 or 8, wherein the source of scrubbed syngas has a yield, flow rate, and / or composition that varies over time.

17. 17. The method of claim 16, wherein the variability in the cleansed syngas source is due to the variable nature of heterogeneous waste biomass, waste, and / or plastic waste feedstocks.

18. 9. The method of any one of claims 1 to 3 or 8, wherein the clean solvent is cooled before being recycled to the at least one absorption unit.

19. 13. The method of claim 12, wherein the thermal stripper comprises a column including at least one of a reboiler and a condenser.

20. The non-flammable CO ２ The rich stream is further used as an inert gas, captured for carbon capture and storage (CCS), and / or sold as commercial CO ２ The method of any one of claims 1 to 3 or 8, wherein

21. 9. The method of any one of claims 1 to 3 or 8, further comprising treating the clean syngas stream with at least one solid adsorbent bed before or after mixing the clean syngas stream with hydrogen.

22. At least one adsorbent bed comprises an alumina-based adsorbent for HCl and halogen removal, an alumina-based adsorbent for HCl, halogens, and H ２ ZnO-based adsorbent for removal of S, COS, CS ２ and a Cu-based adsorbent for removing arsine, and an adsorbent for removing carbonyls.

23. 9. The method of claim 2, 3 or 8, wherein the absorption unit is a column comprising at least three mass transfer zone sections, alternatively at least four mass transfer zone sections.

24. 9. The method of claim 2, 3 or 8, wherein the at least one absorption unit mass transfer zone section is provided in a separate column.

25. The clean syngas stream in the purification unit has less than 100 ppbv, less than 10 ppbv, or alternatively less than 5 ppbv of HCN and NH ３ The method according to any one of claims 1 to 3 or 8, wherein

26. 9. The method of any one of claims 1 to 3 or 8, wherein the clean syngas stream in the purification unit achieves less than 10 ppmv, less than 5 ppmv, less than 1 ppmv, or alternatively less than 0.1 ppmv bound sulfur species.

27. 22. The method of claim 21, wherein the clean syngas stream in the solid adsorbent bed achieves less than 10 ppbv, or alternatively less than 5 ppbv, of sulfur species, halogen species, arsine, and / or metal carbonyls.

28. 28. The method of claim 27, wherein the halogen species is HCl, HF, HBr, or a combination thereof.

29. 28. The method of claim 27, wherein the metal is Ni, Fe, or a combination thereof.

30. H in the clean syngas stream ２ The S concentration is adjusted to achieve a specific desired concentration to meet the requirements of the downstream syngas conversion unit, while low levels of HCN and / or NH ３ 9. The method of any one of claims 1 to 3 or 8, wherein the concentration is achieved.

31. The H in the clean syngas stream ２ 31. The method of claim 30, wherein the S concentration is maintained below 200 ppmv.

32. The H in the clean syngas stream ２ 31. The method of claim 30, wherein the S concentration is maintained below 100 ppmv.

33. 9. The method of any one of claims 1 to 3 or 8, wherein the hydrogen is taken from an external source.

34. 34. The method of claim 33, wherein the captured hydrogen is derived from a renewable source and / or a source with low carbon intensity.

35. The captured hydrogen is generated from renewable electricity, low carbon intensity electricity-powered water electrolysis, biogas reforming, steam reforming, a low carbon intensity (CI) hydrogen source, or a low CI waste hydrogen source. ２ 34. The method of claim 33, wherein the source is derived from the

36. 9. The method of any one of claims 1 to 3 or 8, wherein the purification unit comprises chilled methanol as a solvent.

37. 9. The method of any one of claims 1 to 3 or 8, wherein the equilibrium syngas stream meets the stoichiometric ratio requirements of the syngas conversion unit to produce fuels, chemicals, or Fischer-Tropsch products.

38. 38. The method of claim 37, wherein the chemical is methanol and / or ethanol.

39. 38. The method of claim 37, wherein the Fischer-Tropsch product is diesel, kerosene, jet fuel, and / or naphtha.

40. The method of any one of claims 1 to 3 or 8, wherein the scrubbed synthesis gas is from the gasification and / or reforming of a carbonaceous material.

41. The method of any one of claims 1 to 3 or 8, wherein the source of scrubbed syngas is derived from a carbonaceous material.

42. 42. The method of claim 41 , wherein the carbonaceous material comprises plastics, metals, inorganic salts, organic compounds, industrial waste, recycling facility waste, automobile fluff, municipal solid waste, ICI waste, C&D waste, refuse-derived fuel (RDF), solid recovered fuel, sewage sludge, used utility poles, railroad ties, wood, tires, synthetic fibers, carpet, synthetic rubber, fossil fuel-derived materials, expanded polystyrene, polyfilm flock, building wood materials, or any combination thereof.

43. 42. The method of claim 41 , wherein the carbonaceous material is biomass, biomass-rich waste, plastic-rich waste, or waste material.

44. 42. The method of claim 41 , wherein the carbonaceous material is a plastic, rubber, or tire-rich waste feedstock.

45. CO ２ CO injected from an external source or another process effluent ２ into the clean syngas stream along with the external source of hydrogen to produce a more carbon-enriched equilibrium syngas that meets the stoichiometry of desired end products, thereby further increasing the production of said desired end products.

46. Additional CO ２ The source of CO ２ By adding a recovery and purification unit, high quality and / or ultra clean CO 2 can be recovered in the purification unit. ２ 46. ​​The method of claim 45, wherein a flow is generated.

47. The CO ２ The recovery and purification unit may include primary and / or secondary CO ２ A column is provided. ・Medium quality CO ２ However, the primary CO ２ produced in a column, and / or ・High quality CO ２ However, the secondary CO ２ Generated in the column, 47. The method of claim 46.

48. Some or all of the loaded solvent from the first recycle loop is recycled to the primary and / or secondary CO ２ Used as a washing medium in columns, the CO in the second recirculation loop ２ and the sulfur species-loaded solvent is ２ fed to the bottom of the column, The primary CO ２ CO from the bottom of the column ２ and the sulfur species-laden solvent is ２ is fed to the column, The secondary CO ２ The concentrated sulfur species-laden solvent from the bottom of the column is fed to the stripping unit.

48. The method of claim 47.

49. The high-quality CO ２ is further treated with a solid adsorbent to obtain ultra-high CO ２ 48. The method of claim 47, wherein the method generates a quality.

50. The ultra-high CO ２ Quality, admixing the clean syngas stream with the external source of hydrogen to produce a carbon-enriched equilibrium syngas that meets the stoichiometry of the desired end products, thereby further increasing the production of the desired end products; - Sold off-site, and / or sent for storage, 50. The method of claim 49, wherein

51. The generated ultra-high CO ２ The quality, along with the additional captured hydrogen, ２ and CO ２ to a separate second synthesis gas conversion unit that produces desired end-products.

52. 52. The method of claim 51, wherein the second synthesis gas conversion unit is a methanol catalytic reactor, a Fischer-Tropsch reactor using an iron-based catalyst, or an ethanol reactor using a microbial biocatalyst.

53. The synthesis gas conversion unit is ２ and CO are converted in situ to H ２ and CO ２ 53. The method of claim 52, wherein:

54. Prior to the synthesis gas conversion unit, ２ 9. The method of any one of claims 1 to 3 or 8, further comprising a reverse water gas shift (RWGS) unit in which a portion of said carbon monoxide is converted along with a portion of said hydrogen to generate additional carbon monoxide.

55. The method of claim 54, further comprising mixing CO with a portion of the clean syngas to generate an elevated CO clean syngas.

56. The CO ２ is recycled to the carbonaceous feedstock gasification and / or reforming unit to remove H from the scrubbed synthesis gas source. ２ 9. The method of any one of claims 1 to 3 or 8, wherein the CO / CO ratio is reduced, the overall CO yield and production is increased, and an enhanced CO scrubbed syngas and an enhanced CO clean syngas are generated.

57. 56. The method of claim 55, wherein the CO2-enriched clean syngas is mixed with hydrogen to produce a balanced syngas stream, the balanced syngas stream meeting the stoichiometric ratio requirements of the syngas conversion unit.

58. 9. The method of any one of claims 1 to 3 or 8, wherein the purification unit comprises a stripping unit including a split-load stripper column having at least top and bottom mass transfer zone sections, wherein nitrogen species-laden methanol is fed to the top of the stripper column and above the top mass transfer zone, and wherein the sulfur species-laden methanol is fed to the middle of the stripper column between the top mass transfer zone section and the bottom mass transfer zone section.

59. The purification unit is configured to obtain greater than 99% H in the clean syngas. ２ 9. The method according to claim 1, wherein the CO recovery rate is achieved.

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